For those of you that design networks or suggest designs do you still feel that layer firewalls (from different vendors) is still a valuable part of defensive in depth? From your experience, do companies tend to use this in the SMB enterprises?

Just want to get someone else's perspective. I am submitting a proposal for our new network design on Wednesday and the other guy and I have some very, very different opinions.

Personally, as long as you are using a "good" firewall (easy to administer, secure, works for you), then I would not go with a different vendor if the same group will be administering a lot of other equipment as well. I do not think the overhead is worthwhile, and particularly not so if you use firewall management software from the same vendors (logging, configuration management, etc.).

Oh we will be using vlans in our new design. I personally feel like since I am the one who will be handling the firewall admin work, I should stick with one vendor and expertly configure it and use a solid IDS implementation to pick up the slack.